LONDON, Sept 08, 2016: An international team of researchers has found that a stellar system classified as a globular cluster for the 40-odd years since its detection actually has properties uncommon for a globular cluster that make it the ideal candidate for a living fossil from the early days of the Milky Way.

The cluster, known as Terzan 5 — 19,000 light-years from Earth- harbours stars of hugely different ages — an age-gap of roughly seven billion years and bridges the gap in understanding between our galaxy’s past and its present, the study said.

“Such galactic fossils allow astronomers to reconstruct an important piece of the history of our Milky Way,” explained lead author of the study Francesco Ferraro from University of Bologna in Italy.

While the properties of Terzan 5 are uncommon for a globular cluster, they are very similar to the stellar population which can be found in the galactic bulge, the tightly packed central region of the Milky Way.

These similarities could make Terzan 5 a fossilised relic of galaxy formation, representing one of the earliest building blocks of the Milky Way.

“Terzan 5 could represent an intriguing link between the local and the distant Universe, a surviving witness of the Galactic bulge assembly process,” Ferraro said.

The team scoured data from the Advanced Camera for Surveys and the Wide Field Camera 3 on board Hubble, as well as from a suite of other ground-based telescopes.

They found compelling evidence that there are two distinct kinds of stars in Terzan 5 which not only differ in the elements they contain, but have an age-gap of roughly seven billion years.

The ages of the two populations indicate that the star formation process in Terzan 5 was not continuous, but was dominated by two distinct bursts of star formation.

“This requires the Terzan 5 ancestor to have large amounts of gas for a second generation of stars and to be quite massive. At least 100 million times the mass of the Sun,” co-author of the study Davide Massari from National Institute for Astrophysics (INAF) , Italy.

Countless galaxies exist in the universe, each hiding secrets that humankind is yet to unearth. Pixabay

NASA’s scientists unearthed a relic galaxy

This relic galaxy have double as stars as the milky way

This can be a new landmark research

Using NASA’s Hubble Space Telescope, astronomers have unearthed a “relic galaxy” in the Milky Way’s backyard. The galaxy NGC 1277, lies near the centre of the Perseus cluster of over 1,000 galaxies, located 240 million light-years away.

NASA’s hubble discovered relic galaxy. Pixabay

The findings, published in the journal Nature, showed that the relic galaxy has twice as many stars as our Milky Way, but physically it is as small as one quarter the size of our galaxy. Essentially, NGC 1277 is in a state of “arrested development”. Further, the scientists found that NGC 1277 does not have the same kinds of globular clusters that other large galaxies have.

While massive galaxies tend to have both metal-poor (appearing blue) and metal-rich (appearing red) globular clusters, NGC 1277 is almost entirely lacking in blue globular clusters. This suggests that NGC 1277 never grew further by gobbling up surrounding galaxies.

“I’ve been studying globular clusters in galaxies for a long time, and this is the first time I’ve ever seen this,” said Michael Beasley, of the Instituto de Astrofisica de Canarias at the University of La Laguna, Spain.

NGC 1277 started its life with a bang long ago, ferociously churning out stars 1,000 times faster than seen in our own Milky Way today. But it abruptly went quiescent as the baby boomer stars aged and grew ever redder.

Relic galaxy have more stars than milky way.

The very rare and odd assemblage of stars has remained essentially unchanged for the past 10 billion years, scientists said. In addition, NGC 1277 also has a central black hole that is much more massive than it should be for a galaxy of that size.

This reinforces the scenario that the supermassive black hole and dense hub of the galaxy grew simultaneously, but the galaxy’s stellar population stopped growing and expanding because it was starved of outside material, the study showed. While Hubble has spotted relic galaxies before, but this one is by far the closest.

“We can explore such original galaxies in full detail and probe the conditions of the early universe,” said Ignacio Trujillo, from the varsity.

For the study, the team started looking for “arrested development” galaxies in the Sloan Digital Sky Survey and found 50 candidate massive compact galaxies. IANS